1. The Field of the Invention
The invention relates to a tool holder for holding a tool and for rotationally coupling the tool to a machine tool, wherein the tool holder has a conduit for directing a coolant and/or lubricant through to the tool from a coolant and/or lubricant source, wherein the tool has a conduit section for directing the coolant and/or lubricant to a machining point, and wherein, in the fitted state of the tool in the tool holder, the conduit of the tool holder is in contact with the conduit section of the tool at a coupling point, such that coolant and/or lubricant flows or can flow from the conduit of the tool holder into the conduit section of the tool. Furthermore, the invention relates to a method for operating such a tool holder.
2. The Relevant Technology
A tool holder of this type is known from DE 296 24 433 U1. Here, a spindle device for a machine tool is described in which two feed path systems for separately directing air and liquid into a spindle are provided. Furthermore, a mist-generating device is provided which mixes air and liquid fed through this feed path system and discharges a mist-like mixture in order to lubricate or cool the tool at its machining point. It has proved successful, with such “minimum quantity lubrication”, to use said oil mist for cooling or lubricating the tool in order to ensure effective machining by the tool with an adequate tool life.
In a design of the type mentioned at the beginning, the conduit is placed against the conduit section in an axially abutting manner in order to be able to supply the machining point with coolant and/or lubricant even in an interchangeable tool. In this case, it has been recognized as a disadvantage that segregation of the oil mist can take place in the event of leakages at the coupling point between conduit and conduit section, i.e. the oil can separate from the oil mist and lead to contamination of the tool holder. To the same degree, the oil in the cooling lubricant is of course reduced in this case, which has corresponding negative effects on the cutting process.
A tapping chuck for a tap with minimum quantity lubrication is known from DE 198 21 186 C1, which tapping chuck has an axially central lubricant passage with an axially displaceable coolant tube for a lubricant aerosol and a machine-side minimum quantity lubrication source, from which the lubricant aerosol is directed to the longitudinal bore of the tap. The coolant tube is pressed into its engagement position against the longitudinal bore of the tap by the aerosol pressure acting on its inner end faces, irrespective of the axial position of the tap, and is preloaded outwards by a spring. As a result, the sealing effect at the coupling point between coolant tube and tap is improved.
DE 10 2005 050 754 B4 discloses a tool holder for minimum quantity lubrication in which a coolant and/or lubricant tube for an aerosol provided as coolant and/or lubricant bears against a sealing ring inserted in the tool for sealing said coolant and/or lubricant tube at the end face thereof.